About: Carroll rearrangement is a(n) research topic. Over the lifetime, 1483 publication(s) have been published within this topic receiving 23513 citation(s).
01 May 1976-Journal of the American Chemical Society
01 Feb 1970-Journal of the American Chemical Society
01 Dec 1988-Chemical Reviews
01 Aug 1972-Journal of the American Chemical Society
07 Jul 2010-Journal of the American Chemical Society
TL;DR: Investigations demonstrate that the counterion of the azolium salt plays a key role in the formation of the catalytically active species in the synthesis of enantioenriched kojic acid derivatives.
Abstract: In the presence of a chiral azolium salt (10 mol %), enols and ynals undergo a highly enantioselective annulation reaction to form enantiomerically enriched dihydropyranones via an N-heterocyclic carbene catalyzed variant of the Claisen rearrangement. Unlike other azolium-catalyzed reactions, this process requires no added base to generate the putative NHC-catalyst, and our investigations demonstrate that the counterion of the azolium salt plays a key role in the formation of the catalytically active species. Detailed kinetic studies eliminate a potential 1,4-addition as the mechanistic pathway; the observed rate law and activation parameters are consistent with a Claisen rearrangement as the rate-limiting step. This catalytic system was applied to the synthesis of enantioenriched kojic acid derivatives, a reaction of demonstrated synthetic utility for which other methods for catalytic enantioselective Claisen rearrangements have not provided a satisfactory solution.